At present there exists a wide range of threaded protectors, some of which are mentioned below by way of reference.
U.S. Pat. No. 6,135,156 discloses a closure for a tubular element open ends, wherein said open ends adopt the form of a threaded sleeve and are coupled to a cap with annular skirt which covers said open ends. Said cap with annular skirt is attached to the ends of said tubular element by means of a nut which thread matches that of the sleeve.
U.S. Pat. No. 6,196,270 and U.S. Pat. No. 6,367,508 disclose threaded protectors intended for the protection of threads of tubular elements ends, said protectors including a base portion, a threaded portion which axially extends from a first end of the base portion, said thread portion matching the threaded portion of the tubular elements ends, said protectors being indistinctly configured as male or female protectors, further including elongated annular abutting elements which axially extend from a second end of the base portion. Abutting elements are of average length and width such that the relation between both magnitudes is of at least 2.
Present threaded protectors are difficult to fit due to a possible crossing between protector and tube, they do not seal well and thus allow water and dust to enter, they are not easy to remove in situ, and they are not recyclable because they sweep grease off the tubular element when same are threaded whereby said grease remains on the protector wall. Upon contacting the tubular element thread they contaminate same with metal or plastic particles. Protectors may have a wide diversity of threads, which makes it difficult to standardized the product, being necessary in some cases the delivery of certain protectors by air when facing an urgency due to lack of stock, which implies higher costs.